Electrical switches

ABSTRACT

An electrical switch of the intermittently operating type comprises a resilient metal vane carrying a heat-extensible metal strip and a movable contact electrically connected with the strip. The movable contact is movable towards and away from a fixed contact as the resilient vane flexes as permitted by the metal strip. The vane is of rectangular form and the metal strip is connected at its ends to diagonally opposite corners thereof. The vane is provided with two sets of embossments thereon. One set of embossments is shallower than the other set and is formed to project from one surface of the vane whilst the other set of embossment projects from the other surface of the vane.

United States Patent Bradbury et al. 1 1 Feb. 4, 1975 15 1 ELECTRICAL SWITCHES 2,870,292 1/1959 Welsh .1 3.171130 3,218,4[5 11/1965 Voorman, Jr 337/136 [75] i Y 3,711,808 1/1973 Kamiyama et =11 331/135 B i I 9 "mmgham of England Primary ExaminerArthur P. Grimley g ee ITlhe Lttllcag ElectrLcal Cgmplanyi Attorney, Agent, or Firm-Holman & Stern imite irming am. ng an [22] Filed: July 25, 1973 7 ABSTRACT [21] Applbio-1382382 An electrical switch of the intermittently operating type comprises a resilient metal vane carrying a heat- 30 Foreign Application p i i m extensible metal strip and a movable contact electri- July 25 1972 GM Britain 34684, cally connected wlth the strip. The movable contact 1s movable towards and away from a fixed contact as the [52] CL 337/135 337/141 resilient vane flexes as permitted by the metal strip. [5 l] IL Cl. i 6mm The vane is of rectangular form and the metal strip is [58] Field of I41 39] connected at its ends to diagonally opposite corners thereof. The vane is provided with two sets of embossments thereon. One set of embossments is shallower [56] Raferences Cited than the other set and is formed to project from one surface of the vane whilst the other set of embossment 2 166 238 SDTATES PATENTS 33 I X projects from the other surface of the vane.

avis 7 136 2,861,149 11/1958 Hollis et a1 337/136 3 Claims, 7 Drawing Figures 1 ELECTRICAL SWITCHES This invention relates to electrical switches of the intermittently operating type. Such switches are commonly used in direction indicator control circuits for motor vehicles. More particularly, the invention relates to an electrical switch of the intermittently operating type which comprises a body. a fixed contact on the body, a resilient vane mounted on the body to be flexed between a first position and a second position. the vane being embossed so that flexing occurs with a snap ac tion and so that the vane is inherently biased into its second position, a contact movable with the vane and arranged to engage the fixed contact when the vane is in one of its positions and to be disengaged with the fixed contact when the vane is in the other of its positions, and a heat extensible, electrically conducting strip connected to the vane so as to hold the latter in its first position when the strip is unheated but to allow the vane to snap into its second position when the strip is heated, said strip being electrically connected between the movable contact and a terminal on the body. Such an electrical switch will hereinafter be referred to as an electrical switch as defined herein.

It has previously been proposed to provide an electrical switch as defined herein in which the vane is embossed by striking one side of the vane with a tool so that recesses are formed therein which define projections on the opposite side of the vane. In one such type of switch as defined herein, the vane is of rectanguiar shape and the strip is attached to diagonally opposed edges of the vane. The recesses are of elongate form and are axially spaced apart on the diagonal joining of the two aforesaid corners of the vane.

However, with such embossments, consistent results throughout the life of the switch are not always obtained and the desired distance of movement between the first and second positions is also not consistent throughout the life of the switch.

An object of the present invention is to provide an electrical switch as defined herein in which the abovementioned disadvantage is obviated or mitigated.

According to the present invention, there is provided an electrical switch as defined herein, wherein the vane is formed with two sets of embossments thereon, one set of embossments being formed by recesses formed in one surface of the vane so as to define projections on the other surface of the vane and the other set of embossments being formed by recesses in the said other surface of the vane so as to define projections on the said one surface of the vane.

Preferably, the recesses of the said one set of embossments are shallower than the recesses of the said other set of embossments.

Most advantageously. the vane is of rectangular form, the ends of the heat extensible strip are respectively connected to diagonally opposite corners of the vane so that the strip extends diagonally across the said one surface of the vane, the recesses of the said other set of embossments comprise a pair of longitudinally spaced elongate recesses on the diagonal joining the said diagonally opposite corners of the vane, and the recesses of the said one set of embossments comprise a pair of longitudinally spaced elongate recesses extending along the diagonal joining the other diagonally opposite corners of the vane.

An embodiment of the present invention will now be described. by way of example, with reference to the accompanying drawing. in which:-

FIG. I is an end view of an electrical switch as defined herein, according to the present invention,

FIG. 2 is a plan view of the underside of the vane shown in FIG. I,

FIG. 3 is a plan view from above of the vane shown in FIG. 2,

FIG. 4 is a side elevational view of the electrical switch according to the present invention depicting the vane in its first position thereof;

FIG. 5 is a side elevational view of the electrical switch of the invention depicting the vane in a second position thereof;

FIG. 6 is a perspective illustration of the top side of the vane similar to that depicted in FIG. 3; and

FIG. 7 is a sectional view of the vane of FIG. 6 taken along lines 7-7 thereof illustrating the direction of projection of the vane embossments.

Like parts are designated with the same reference numeral throughout the various drawing views.

Referring to the drawings, the electrical switch comprises a body 10 having a pair of terminals II and I2 mounted thereon. The terminal II is electrically con nected with a stud-type fixed contact I3 having a contact pad 14 carried thereon. The terminal 12 is electrically connected with a metal support plate I5 having an integral post I6 extending therefrom. A spring steel vane 17 of rectangular form is tack welded to the post 16 at a point 18 which is intermediate the ends of one of the longitudinal edges of the vane I7.

Referring now more particularly to FIGS. 3 and 6, the vane 17 has a heat extensible, electrically conducting metal strip 19 extending diagonally across one surface thereof. The strip 19 is connected at its ends 20 and 21 with diagonally opposed corners 22 and 23, respectively. of the vane 17. The vane I7 is provided with embossments thereon in the form of two pairs of recesses 24 and 25. The set of recesses 24 are formed in the said other surface of the vane 17, i.e., that surface of the vane opposite to the surface over which the strip [9 extends, so as to define projections on said one surface of the vane 17. As can be seen from FIG. 3, FIG. 6 the recesses 24 are of elongate form, are longitudinally spaced apart, and extend along the diagonal of the vane joining the corners 22 and 23 thereof. The other set of recesses 25 are formed in the said one surface of the vane 17 so as to define projections on the said other surface of the vane 17, i.e., that surface of the vane opposite to the strip 19 as best shown in FIG. 7. The set of recesses 25 are of elongate form, are spaced apart longitudinally on the diagonal joining the remaining two diagonally opposed corners 26 and 27 of the vane I7 and are shallower than the recesses 24.

The provision of the embossments on the vane I7 as described above is such that the latter can be flexed be tween a first position as shown in FIGS. I and 4, and a second position as shown in FIG. 5 so that movement of the vane 17 between the positions occurs with a snap action. Furthermore. the embossments cause the vane to be inherently biassed into its second position. However, the length of the strip 19 is so arranged that it holds the vane I7 in its first position (as shown in FIG. I and FIG. 4) when the strip 19 is unheated. When strip I9 is heated due to passage of current therealong, it extends and permits the vane 17 to snap into its second position. Referring to FIG. 2, the strip 19 is provided with a central contact 28 which is electrically connected with the vane 17 via the strip 19 whose ends 20 and 2! are connected with the corners 22 and 23 of the vane l7 as described herein above. The contact 28 is thus mounted for movement with the vane 17 and is electrically connected with the terminal 12 since the vane 17 is electrically connected with the support plate 15 via the integral post 16.

in use. the vane 17 is normally held in its first position by the strip 19.

in the first position of the vane l7. the contact 28 engages the contact pad 14 of the fixed contact 13 and thereby causes the terminals H and 12 to be interconnected through the intermediary of the strip I9. Thus, when a current is passed between terminals 11 and T2, the effect of the current passing through strip 19 causes the latter to be heated and therefore to extend. Extension of the strip 19 causes. as described above, the vane l7 to snap into its second position (see FIG. 5) in which the contact 28 is disengaged from the fixed contact 13. In the second position. no current flows through the strip [9 which then cools down and contracts so as to snap the vane 17 into its first position thereby reestablishing the engagement between the contacts 28 and 13 so that the current again flows through strip 19 which extends and causes further disengagement of the contacts 28 and 13. In this manner. the electrical switch operates intermittently The provision of the set of recesses in the position described herein above enables the force required to snap the vane 17 into its first position to be reduced compared with an arrangement in which the set of recesses 25 is not provided. It is found furthermore that there is less likelihood of the strip 19 fracturing during use and that the relationship between the snap load and the distance between the first and second positions can be set to the desired value by appropriate choice of the relative depths of embossment of the respective sets of recesses 24 and 25.

We claim:

I. An electrical switch of the intermittently operating type comprising a body. a fixed contact on said body, a resilient. rectangular vane mounted on said body to be flexed between a first position and a second position. said vane being embossed so that flexing occurs with a snap-action and so that said vane is inherently biased into its second position. a contact movable with said vane and arranged to engage said fixed contact when said vane is in one of its positions and to be displaced from said fixed contact when said vane is in the other of its positions. and a heat extensible. electrically conducting strip connected to diagonally opposite corners of said vane so as to hold the latter in its first position when said strip is unheated but to allow said vane to snap into its second position when said strip is heated. said strip being electrically connected with said movable contact and a terminal on said body. wherein said vane is formed with two sets of embossments thereon. one set of embossments being formed by recesses formed in one surface on said vance so as to define projections on the other surface of said vane. and the other set of embossments being formed by recesses in said other surface of said vane so as to define projec tions on said one surface of said vane. said recesses of said other set of embossments comprising a pair of longitudinally spaced elongate recesses on the diagonal joining said diagonally opposite corners of said vane, and said recesses of said one set of embossments comprising a pair of longitudinally spaced elongate recesses extending along the diagonal joining the other diagonally opposite corners of said vane.

2. The electrical switch according to claim 1, wherein said recesses of said on set of embossments are shallower than said recesses of said other set of embossments.

3. The electrical switch according to claim 1, wherein said vane is secured to a post electrically connected with said terminal on said body intermediate the ends of one of the longitudinally edges of said vane.

5' t I R i 

1. An electrical switch of the intermittently operating type comprising a body, a fixed contact on said body, a resilient, rectangular vane mounted on said body to be flexed between a first position and a second position, said vane being embossed so that flexing occurs with a snap-action and so that said vane is inherently biased into its second position, a contact movable with said vane and arranged to engage said fixed contact when said vane is in one of its positions and to be displaced from said fixed contact when said vane is in the other of its positions, and a heat extensible, electrically conducting strip connected to diagonally opposite corners of said vane so as to hold the latter in its first position when said strip is unheated but to allow said vane to snap into its second position when said strip is heated, said strip being electrically connected with said movable contact and a terminal on said body, wherein said vane is formed with two sets of embossments thereon, one set of embossments being formed by recesses formed in one surface on said vance so as to define projections on the other surface of said vane, and the other set of embossments being formed by recesses in said other surface of said vane so as to define projections on said one surface of said vane, said recesses of said other set of embossments comprising a pair of longitudinally spaced elongate recesses on the diagonal joining said diagonally opposite corners of said vane, and said recesses of said one set of embossments comprising a pair of longitudinally spaced elongate recesses extending along the diagonal joining the other diagonally opposite corners of said vane.
 2. The electrical switch according to claim 1, wherein said recesses of said on sEt of embossments are shallower than said recesses of said other set of embossments.
 3. The electrical switch according to claim 1, wherein said vane is secured to a post electrically connected with said terminal on said body intermediate the ends of one of the longitudinally edges of said vane. 